1. Field of the Invention
The present invention relates to a circuit for driving an electronic device, and particularly, to a circuit for driving an electronic device that converts electric power into light or heat energy.
2. Description of the Related Art
Examples of electronic devices that convert electric power into light or heat energy are direct-current driven laser diodes such as pump laser diodes for optical fiber amplifiers, and Peltier elements. These devices require a high-output drive circuit, which must be compact and operate on low power.
Conventional drive circuits for the laser diodes and Peltier elements usually employ an analog control circuit composed of one or more bipolar transistors or field effect transistors (FETs). The analog control circuit is connected to a power source and provides the laser diode or Peltier element with a drive current. Each bipolar transistor or FET of the analog control circuit always consumes a product of the drive current and a voltage applied to both ends of the transistor. This large power consumption deteriorates the efficiency of the drive circuit, requires a high voltage to be applied to the ends of each transistor, increases the size of each transistor, and decreases the space factor of the drive circuit.